upd

content/docs/algorithms-101/algorithms.md

@@ -21,14 +21,27 @@ published: true
 ## Sort
 
 ```python
-def insertion_sort(a_list):
-    for i in range(1, len(a_list)):
-        value = a_list[i]
-        while i > 0 and a_list[i - 1] > value:
-            a_list[i] = a_list[i - 1]
-            i = i - 1
-            a_list[i] = value
-    return a_list
+def insertion_sort(array):
+    for i in range(1, len(array)):
+        value = array[i]
+        while i > 0 and array[i - 1] > value:
+            array[i] = array[i - 1]
+            i -= 1
+            array[i] = value
+    return array
+```
+
+```python
+def selection_sort(array):
+    for i in range(len(array) - 1):
+        min_value = i
+        for j in range(i + 1, len(array)):
+            if array[j] < array[min_value]:
+                min_value = j
+        temp = array[min_value]
+        array[min_value] = array[i]
+        array[i] = temp
+    return array
 ```
 
 
@@ -354,26 +367,16 @@ def backtrack(some_len_data):
             i += 1
 ```
 
-### Resources
-- https://algo.monster/problems/backtracking
+**Links:**
 
-## Trie
+- https://algo.monster/problems/backtracking
 
-```python
-class Node:
-    def __init__(self, value):
-        self.value = value
-        self.children = {}
-
-    def insert(self, s, idx):
-        # idx: index of the current character in s
-        if idx != len(s):
-            self.children.setdefault(s[idx], Node(s[idx]))
-            self.children.get(s[idx]).insert(s, idx + 1)
-```
 
 ## Resources
 
 - https://www.geeksforgeeks.org/learn-data-structures-and-algorithms-dsa-tutorial/
 - https://algo.monster/templates
 - https://interviewnoodle.com/grokking-leetcode-a-smarter-way-to-prepare-for-coding-interviews-e86d5c9fe4e1
+- [data structures](https://github.com/OpenGenus/cosmos)
+- [Competitive Programming Library](https://github.com/cheran-senthil/PyRival)
+- [Algorithms for Competitive Programming](https://cp-algorithms.com/)

content/docs/algorithms-101/codeforces.en.md → content/docs/algorithms-101/codeforces/_index.en.md

@@ -6,7 +6,7 @@ tags: []
 categories: [Algorithms]
 series:
 date: 2023-02-03
-lastmod: 2023-02-07
+lastmod: 2023-02-09
 featuredImage:
 draft: false
 weight: 40
@@ -315,8 +315,64 @@ def solve():
 ```
 
 ### TODO F. Range Update Point Query
+
 https://codeforces.com/contest/1791/problem/F
 
+There are two types of inputs (cases) (in addition to array `a` and `n` of test cases):
+1. line with **two** elements: `2 x`. Starts with `2`
+2. line with **three** elements: `1 l r`. Starts with `1`
+
+In 1st case: print array `a`
+
+In 2nd case: update the value of `𝑎𝑖` to the sum of its digits.
+
+**Slow Solution:**
+
+```python
+def sum_of_digits(n):
+    sum = 0
+    while n:
+        sum += n % 10
+        n //= 10
+    return sum
+
+def solve():
+    n, q = map(int, input().split())
+    a = list(map(int, input().split()))
+    while q:
+        q -= 1
+        t, *params = map(int, input().split())
+        if t == 1:
+            l, r = params
+            for i in range(l-1, r):
+                a[i] = sum_of_digits(a[i])
+        else:
+            x, = params
+            print(a[x-1])
+
+t = int(input().strip())
+for _ in range(t): # attempts
+    solve()
+```
+
+This solution is slow because of loop:
+
+    for i in range(l-1, r):
+        a[i] = sum_of_digits(a[i])
+
+The key here is the following: after the operation is applied on **a<sub>i</sub>**
+
+
+**Good to know**
+
+- [Segment Tree template tutorial](../data-structures/segment-tree)
+- [A Visual Introduction to Fenwick Tree | medium](https://medium.com/carpanese/a-visual-introduction-to-fenwick-tree-89b82cac5b3c)
+- [Fenwick Tree](https://cp-algorithms.com/data_structures/fenwick.html)
+- [Segment Tree](https://cp-algorithms.com/data_structures/segment_tree.html)
+- [Дерево отрезков | algorithmica](https://ru.algorithmica.org/cs/segment-tree/)
+- [Дерево Фенвика | algorithmica](https://ru.algorithmica.org/cs/range-queries/fenwick/)
+- [Дерево Фенвика | habr](https://habr.com/ru/post/112828/)
+
 ### TODO G1. Teleporters (Easy Version)
 https://codeforces.com/contest/1791/problem/G1
 
@@ -326,9 +382,21 @@ https://codeforces.com/contest/1791/problem/G2
 
 ## Links
 
+- [Python Visualize/Debug code online](https://pythontutor.com/visualize.html#mode=edit)
 - [Python collections.Counter](https://docs.python.org/3/library/collections.html#collections.Counter)
 - https://github.com/archishmanghos/DSA-Contests/
 - https://github.com/debochdilamo/Competative-Programming/tree/CodeForces-Solutions
 - https://github.com/DilamoWondimu/Competative-programming/tree/main/CodeForces-Solutions
 - https://github.com/hkirat/Algorithmic-Resources
-- https://github.com/valentk777/Competitive-Programming/
+- https://github.com/valentk777/Competitive-Programming/
+- [Competitive Programming Library](https://github.com/cheran-senthil/PyRival)
+
+
+
+
+
+
+## Codeforces Round #850 (Div. 2)
+
+https://codeforces.com/contest/1785/
+https://codeforces.com/blog/entry/112493

content/docs/algorithms-101/codeforces/cp-template.en.md

@@ -0,0 +1,60 @@
+---
+title: Python template for contests
+seoTitle: Python template for contests
+description: Python template for contests
+toc: true
+tags: []
+categories: [Algorithms]
+series:
+date: 2023-02-07
+lastmod: 2023-02-09
+# featuredImage:
+draft: false
+weight: 10
+---
+
+
+```python
+import math
+import os
+import sys
+import time
+from collections import defaultdict, Counter
+
+
+INF = sys.maxsize
+
+# ------ INPUTS
+
+inp = lambda: sys.stdin.readline().strip().rstrip("\r\n") #read line as string. Ex: input 1 2 3 => '1 2 3'
+inpi = lambda: int(inp()) #read input as integer. input 1 => 1
+inpl = lambda: list(map(int, inp().split())) #read line as list of integers. Ex: [1, 2, 3]
+inp_strl = lambda: list(inp().split()) #read line as list of strings. Ex: ['1', '2', '3']
+
+list_to_string = lambda _v: "".join(map(str, _v)) # [1,2,3] => '123'
+list_to_string_list = lambda _v: " ".join(map(str, _v)) # [1,2,'3'] => '1 2 3'
+
+
+# ------ SOLUTION
+
+def solve():
+    # input
+
+    return 
+
+
+def run():
+    solve()
+    print(solve())
+
+
+if __name__ == "__main__":
+    LOCAL_TESTS = 0
+    if os.environ.get("LOCAL_TESTS") or LOCAL_TESTS:
+        sys.stdin = open("./input.txt", "r")
+        start_time = time.time()
+        run()
+        print("\n--- %s seconds ---\n" % (time.time() - start_time))
+    else:
+        run()
+```

content/docs/algorithms-101/data-structures/_index.en.md

@@ -0,0 +1,66 @@
+---
+title: Data Structures
+description: null
+authors:
+categories: ['programming', 'Data Structures', 'Codeforces']
+tags: ['Data Structures']
+# series: null
+# featuredImage: null
+toc: false
+weight: 40
+date: 2023-02-09
+lastmod: 2023-02-09
+published: true
+---
+
+
+### Tree
+
+```python
+class Node:
+    def __init__(self, value):
+        self.value = value
+        self.children = {}
+
+    def insert(self, s, idx):
+        # idx: index of the current character in s
+        if idx != len(s):
+            self.children.setdefault(s[idx], Node(s[idx]))
+            self.children.get(s[idx]).insert(s, idx + 1)
+```
+
+### Fenwick Tree
+
+```python
+class Fenwick: #also known as Binary Indexed Tree (BIT)
+    def __init__(self, n):
+        self.n = n
+        self.bit = [0] * (n+1)
+    def add(self, idx, val):
+        while idx <= self.n:
+            self.bit[idx] += val
+            idx += idx & -idx
+    def add_range(self, l, r, val):
+        self.add(l, val)
+        self.add(r+1, -val)
+    def point_query(self, idx):
+        #Calculates the sum of the elements from the beginning to idx
+        ret = 0
+        while idx > 0:
+            ret += self.bit[idx]
+            idx -= idx & -idx
+        return ret
+```
+
+
+- [A Visual Introduction to Fenwick Tree | medium](https://medium.com/carpanese/a-visual-introduction-to-fenwick-tree-89b82cac5b3c)
+- [Fenwick Tree](https://cp-algorithms.com/data_structures/fenwick.html)
+- [Дерево Фенвика | algorithmica](https://ru.algorithmica.org/cs/range-queries/fenwick/)
+- [Дерево Фенвика | habr](https://habr.com/ru/post/112828/)
+
+
+## Resources
+
+- [data structures](https://github.com/OpenGenus/cosmos)
+- [Competitive Programming Library](https://github.com/cheran-senthil/PyRival)
+- [Algorithms for Competitive Programming](https://cp-algorithms.com/)